The present invention generally relates to a contact spring consisting of a longitudinal spring means, in particular for use in an electro-optic circuit.
An electro-optic circuit is known that comprises optic sender and receiver components for transforming an electric output signal to an outgoing optic signal and for transforming a received optic signal to an electric input signal, respectively, connection means for an opto conductor on which the outgoing and received optic signals are transmitted, a sender for the electric output signal, and a receiver for the electric input signal.
Electro-optic circuits of this kind are used e.g. located on a printed circuit card in a telecommunication switch. Each circuit card carries a plurality of such electro-optic circuits and in the switch one or more cabinets can contain a plurality of shielded card magazines, each of which contains a plurality of such circuit cards. For increasing the insensitivity towards EMC, i.e. electromagnetical disturbance radiation, senders and receivers are conventionally located far in on the card as seen from its edge located at an outer cabinet wall, below denominated card front. On the card front there are seated a number of connection devices for connecting an outer opto conductor to two opto conductors leading to the sender and receiver, respectively, of a corresponding sender/receiver pair. For minimizing the risk for interference between sender and receiver of each sender/receiver pair the sender and the receiver are furthermore located remote from each other on the card.
This distribution of the components of the electro-optic circuit counteracts a striving for a more compact architecture of switches of the just described type, while saving or further improving the insensitiveness for EMC, as well as ESD, i.e. electrostatical discharges.
To take care of this it has turned out to be advantageous that the individual circuit forms a module with an electromagnetically shielded housing that contains the optical sender and receiver components and connection means for the opto conductor, and that a two-sided printed circuit arrangement carries the sender and the receiver located shielded from each other on one side each by means of an electrically conducting shielding that is in connection with the housing for forming three Faraday's cages, one for the sender, one for the receiver and one formed of the housing in its entirety.
In an arrangement of the kind just mentioned it is essential that an intimate contact is maintained between grounding parts of the housing parts by contact means taking up the least possible space.
In EP-124701 there is described a device for contact making of printed circuit cards introduced into brackets, in particular for providing ground connection between a housing and the printed circuit card. It includes a spring clip that surrounds the edge of the printed circuit card and is provided with clawlike extensions which engage the contact surfaces of the printed circuit card and which, when the printed circuit card is inserted in the bracket, is in electric contact with this.
EP-447942 describes a contact rib of metallic material for fitting on the edge of a metallic wall element, in order to provide an interference radiation tight connection. The contact rib has a row of individual contact tongues which are stamped free and outwardly bent from the contact rib plane at a distance from each other, and a row of individual clamp elements distributed at a distance from each other along their lengths.